Winter 2002

• Starter Generator Vibration
• Commercial Support Program Termination
• Hot Section Inspection and Overhaul Intervals
• JT15D Troubleshooting Class

Starter Generator Vibration

— Ken Kuchenreuther

Every piece of moving equipment has its own inherent vibration and noise. The same is true of an aircraft in flight. After a while you sense what noises and vibrations are normal and pay no attention to them during the flight. Any abnormal vibration or noise should set off an internal alarm – even if it seems like a small abnormality. On the way to your favorite FBO, try to isolate which side and under what circumstances you heard the noise. Whether the noise can be traced to an engine or not, a good practice upon landing is to have the starter generators removed and disassembled and the bearings checked. Duncan Aviation has found that the starter generator bearings are a leading cause of abnormal vibration. If starter generator vibration is allowed to worsen, severe gearbox or engine damage can result.

A Duncan Aviation customer recently reported abnormal vibration. He thought it was on the right side. We immediately investigated the bearings in the starter generator and found that they needed to be replaced. He flew again and still had a vibration. Upon returning, the left starter generator was removed and inspected, and it was found that those bearings were also bad. The starter generators can be interchanged to troubleshoot and isolate a vibration.

For more information, contact Ken Kuchenreuther at 800.525.2376, E-mail Ken at ken_kuchenreuther@duncanaviation.com or Craig Bohling at 800.228.4277

Commercial Support Program Termination

— Ken Kuchenreuther

Service Bulletin 7568, Commercial Support Program Notification A99018 is scheduled for termination on December 31, 2001. In this Service Bulletin, the condensate trap is removed and a tee fitting installed to help prevent ice formation and to purge contaminants from the P3 supply line to the fuel control unit. Under certain cold ambient conditions, a limited engine response during descent was possible with the condensate trap.

The new part is being offered at no charge under the Commercial Support Program. For those Beechjet owners and others that have JT15D-5 engines, or for those who fly -5B, -5F engines and have not complied with this Service Bulletin, you will want to do so immediately.

If you would like more information about this program, please contact Ken Kuchenreuther at 800.525.2376 or Craig Bohling at 800.228.4277.

Hot Section Inspection and Overhaul Intervals

— Ken Kuchenreuther

From time to time the engine manufacturers adjust overhaul and hot section intervals as driven by the average effect of many variables. Many times, the time between intervals is increased. If you are getting close to an interval, call Duncan Aviation to check the current status. The last service bulletin revision for JT15D series engines is R31 on January 10, 2001. On these important events a little caution can help save a great deal of frustration.

For more info, contact Ken Kuchenreuther at 800.525.2376 or Craig Bohling at 800.228.4277.

JT15D Troubleshooting Class

— Dan Arrick

In the tradition of our Intelligence Faxes, Duncan Aviation will be hosting a 2-day symposium in May 2002. The event will offer a four hour course on the JT15D engine, as well as many other customer-requested topics, including a session on Citation troubleshooting. Many of the sessions will be offered for IA renewal credit. Log on to www.duncanaviation.com/conference for more information.

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